Upgrade to ffmpeg 7.0.1 (channel layout API)

[kartik-venugopal]

Hello, thanks for writing this great utility!

Recently, ffmpeg's channel layout API has changed, and as a result, your code does not compile with newer versions of ffmpeg. I believe mine is 7.0.1.

I was able to make the required changes locally, without much effort. Should be no more than 10 minutes of effort.

It would be great if the code could be adapted to accommodate the new API! Thanks.